ByteDance interview notes, page 26 of 29

FAANG / Big Tech

Most of these ByteDance write-ups come from Software Engineers (194), then Machine Learning Engineers (45) and Data Scientists (17). The most reported rounds are the technical phone screen (227), the system design round (28), the behavioral / leadership round (16) and the onsite coding round (9).

289 interview notes · updated Sep 2026

ByteDance·Software Engineer·Technical Phone Screen

Jun 2026

Bytedance SWE interview that was basically a forensic examination of one of my past projects. They wanted to see if you actually thought through your decisions or just stumbled into them.

Before building this project, what existing or mature infrastructure options did you evaluate as alternatives?
Why did you choose to build this solution rather than adopt one of those existing alternatives?
What was the core problem this project was actually solving? What motivated it?
How did you define success for this project, and how did you set up the metrics to track it?

“This is where I fumbled a bit.”

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ByteDance·Software Engineer·Technical Phone Screen

Jun 2026

Bytedance software engineer screen, one coding problem, pretty standard stuff but the O(log n) constraint makes it clear they want binary search and not just a linear scan.

Given a sorted array of distinct integers and a target value, return the index if the target exists, or the index where it would be inserted to keep the array sorted. Must run in O(log n).

“The O(log n) requirement is basically them telling you to use binary search without saying it.”

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ByteDance·Machine Learning Engineer·Onsite - System Design / Architecture

Jun 2026

Bytedance ML engineer interview with a two-part systems question that covered both model deployment under resource constraints and large-scale video retrieval. Pretty grueling for a single session, lots of ground to cover.

You need to deploy a multimodal large model in production that generates captions for videos, under fixed compute and GPU memory budgets. How do you meet throughput and latency requirements? Walk through model selection, distillation, quantization, batching strategies, frame sampling, KV cache usage, and serving stack choices.
Given a precomputed catalog of video captions and embeddings, design a system that lets brand advertisers quickly find and rank relevant videos for watermarking at scale. Cover vector indexing, hybrid retrieval, filtering, re-ranking, and any further acceleration strategies.

“This is the kind of question where you can talk for 30 minutes and still feel like you barely scratched it.”

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ByteDance·Backend Engineer·Technical Phone Screen

Jun 2026

Bytedance backend round, one algorithmic problem the whole time. Pretty standard tree recursion territory but the edge cases tripped me up more than I expected.

Given two binary trees A and B, determine whether B is a substructure of A. B is a substructure if there exists a node in A where, starting from that node, every node in B matches the corresponding node in A by value and position. B does not need to reach the leaves of A, and a null B is never considered a substructure.

“My first instinct was to just check if B is a subtree, which is wrong.”

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ByteDance·Software Engineer·Technical Phone Screen

Jun 2026

Bytedance SWE interview with a grid traversal problem that had a few extra constraints thrown in to keep things interesting. The fuel mechanic and recharge cells made it trickier than a standard shortest path, and then they hit me with a follow-up about what to do when K blows up the state space.

Given an m x n grid where each cell has a cost, find the minimum total cost path from (0,0) to (m-1, n-1). You have a fuel tank of capacity K that depletes by 1 per move, some cells are blocked entirely, and some cells fully refuel you back to K on entry. Return the minimum cost or -1 if unreachable.
Follow-up: if K can be extremely large, the O(m * n * K) state space becomes impractical. How would you optimize the algorithm?

“The base structure is Dijkstra with state (row, col, fuel), which I got to pretty quickly.”

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ByteDance·Software Engineer·Technical Phone Screen

Jun 2026

Bytedance coding round, graph problem that looks straightforward until you realize there are two separate things to check. Not a bad experience, just a lot riding on one question.

Given n nodes labeled 0 to n-1 and a list of undirected edges, determine whether the graph forms a valid tree.

“I went with Union-Find because I've drilled it enough that it feels safer under pressure.”

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ByteDance·Data Scientist·Technical Phone Screen

Jun 2026

Bytedance Data Scientist interview with a SQL question that looked straightforward but had a subtle deduplication requirement baked in. The kind of problem where you can get a working query pretty fast and still miss the point entirely.

Given a users table with registration timestamps and a posts table with post creation timestamps, write a SQL query that returns, for each calendar date, the count of distinct users who both registered on that date and published at least one post on that same date.

“The dedup part is where people probably slip up.”

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ByteDance·Frontend Engineer·Technical Phone Screen

Jun 2026

Bytedance frontend interview that's basically a resume walkthrough with teeth. They go project by project and expect you to actually know the details, not just summarize.

Walk us through your background and introduce yourself.
For each major project on your resume, explain what you built, your specific role, and the decisions you made.
Describe the most technically or organizationally challenging project you've worked on. What made it hard, what did you personally contribute, what trade-offs did you make, and what was the result?

“Pretty standard opener but they didn't let it stay standard for long.”

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ByteDance·Software Engineer·Technical Phone Screen

Jun 2026

Bytedance SWE interview with a string problem that sounds straightforward until you actually try to implement it cleanly under pressure.

Given a string and an integer k, find the length of the longest substring where every character appears at least k times.

“My first instinct was sliding window and I started going down that path before realizing it gets messy fast because the window validity condition isn't monotonic.”

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ByteDance·Software Engineer·Technical Phone Screen

Jun 2026

Bytedance software engineering interview with a string manipulation problem that looks straightforward until you realize brute force blows up on nested removals. The stack insight is clean once you see it, but getting there under pressure is a different story.

Given a string, repeatedly remove every substring matching the pattern lowercase-uppercase-lowercase (where the first and third characters are the same letter), scanning left to right, until no more such substrings remain. Return the final string.

“My first instinct was to just loop and replace until nothing changes, which works but felt gross.”

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